1. Field of the Invention
The present invention relates to a rotating device including a shaft body supported in a relatively rotatable manner and a bearing body, and a manufacturing method of the rotating device.
2. Description of the Related Art
Rotating devices like a disk drive device are becoming compact and increasing the capacity thereof, and are built in various electronic devices. Such rotating devices are popularly built in, in particular, a hard disk drive that is a kind of disk drive devices of portable electronic devices, such as a laptop computer and a portable music player. The rotating devices like the disk drive device built in such portable electronic devices need improved shock resistance and vibration resistance (hereinafter, referred to as “shock resistance characteristic, etc.,”) so as to withstand a shock due to falling and a vibration when carried in comparison with the rotating devices built in stationary electronic devices like a desktop computer. Moreover, such rotating devices need thinning and weight saving in comparison with the rotating devices built in the stationary electronic devices like a desktop computer. In general, thinning and improvement of the shock resistance characteristic, etc., are in a trade-off relationship.
One of the inventors of the present invention proposes a rotating device that is a disk drive device having a fluid dynamic bearing mechanism formed between a shaft body and a bearing body, and having the shaft body including a shaft fixed to a base in, for example, JP 2010-261580 A. According to the rotating device disclosed in JP 2010-261580 A, a radial dynamic bearing is formed in a space in the radial direction between the shaft body and the bearing body, and a thrust dynamic bearing is formed therebetween in a space in the axial direction.
For the rotating device like the disk drive device disclosed in JP 2010-261580 A, in order to make the shock resistance characteristic, etc., improved, there is a demand to demand the rigidity of a thrust dynamic bearing (hereinafter, referred to as a “thrust rigidity”). In order to improve the thrust rigidity, a technique of reducing a gap between a shaft body structuring a thrust bearing and a member of a bearing body in the axial direction is known.
When, however, the gap between the shaft body and the member of the bearing body is reduced, an adverse effect of a manufacturing error in the dimension of components for such a gap relatively increases. Rotating device may be formed with an attempt to reduce the manufacturing errors in the individual components of the shaft body and the bearing body, but in order to do so, manufacturing of such components needs a large amount of labor works, which may result in the reduction of the yield of the manufacturing of the components. Hence, rotating devices are practically designed based on an assumption that the components have manufacturing errors in dimension within a certain range. In the case of such rotating devices, when the gap between the shaft body and the bearing body is too small, the shaft body and the bearing body may contact with each other while the rotating device is rotating, and in the worst case, those components are highly possibly damaged. Hence, there is a tendency that such a gap is designed largely in consideration of the manufacturing error in such a way that the gap between the shaft body and the bearing body does not become excessively small even if the manufacturing error is present. According to such a circumstance, the manufacturing error in the shaft body and the component of the bearing body disturbs the improvement of the thrust rigidity, and is a technical interruption against the improvement of the shock resistance characteristic, etc.
Under such a background circumstance, the inventors of the present invention recognized that it is necessary to suppress an adverse affect of the manufacturing error in the gap between the shaft body and the bearing body in order to improve the shock resistance characteristics, etc., of the rotating device.
The same is true of not only the rotating devices built in portable electronic devices but also electronic devices of other kinds.
The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a technology of improving conventional rotating devices, and suppressing an adverse effect of a manufacturing error in a gap between a shaft body and a bearing body in an axial direction to avoid a reduction of a shock resistance characteristic, etc., of a rotating device.